Tuning patch-form FSS

The application of a novel biasing technique to tune frequency selective surfaces (FSS) made of patch elements is described. The methodology follows a recently developed technique where the biasing circuit of an active FSS is etched at the rear of a double sided substrate. On this occasion, the structure consists of dipole patches on one side of the thin polyester substrate and the biasing circuit at the rear, electromagnetically hidden by the patches. Varactor diodes are employed to modify the capacitance between the patches. The novel active FSS structure is able to tune a bandstop filter response over a wide frequency range, which could suit applications such as the time dependent modification of the EM architecture of buildings.